Recovery of manganese from compound silicate material



Patented Jan. 30, 1951 .RECOVERY OF MANGANESE FROM COM- POUND SILICATE MATERIAL Robert A. Schoenlaub, Cleveland, Ohio, assignor to Sylvester & Company, Cleveland, Ohio, a

corporation of Ohio No Drawing. Application April 9, 1949, Serial No. 86,603

9 Claims.

In working up compound silicate materials which contain calcium, iron, and manganese, I have found that manganese can be recovered to particular advantage. And, in fact, low-grade manganese sources which involve fundamental combinations of calcium and iron may be worked up to yield profitable amounts of manganese. In addition to natural ore and mineral sources of such compound silicates, there are also applicable slags such as from open hearth steel making.

Manganese is such an essential component of steel and its principal sources are so remote that such a process is economically desirable. Furthermore, if manganese can be easily recovered, more manganese can be carried in a slag, thus greatly facilitating the operation of making steel in the open hearth.

Manganese is a very diflicult substance to extract from low-grade materials. It tends to have a greater affinity for the individual chemical constituents of such a material than the chemical constituents have for each other. Also, manganese resists reduction to such an extent that undesirable elements are reduced before or simultaneously with the manganese. Again, manganese is retained tenaciously by silicate slags. At high temperatures, man anese volatilizes.

In accordance with the present invention, thus, manganese concentrate may be derived from low content manganese compound silicate materials as indicated and this so-separated manganese then may be formed into spiegeleisen, ferromanganese. etc. Thus, as a desirable aspect of the invention, steel manufacture may be facilitated by using more manganese and recovering the manganese which ordinarily has been lost, and recycling such manganese in the operation. This is notably feasible since it costs very little more to recover a large amount than a small amount from a slag.

To the accomplishment of the foregoing and adjusting the composition of the raw material to a range of certain critical proportions as will be detailed hereinafter, and then the material is fired to pyrochemicallyv displace the manganese v and render it separablaas by grinding and treating by physical and/or chemical separating means, and then the manganese concentrates so stitute in a crystal phase or mineral for other oxides of a similar nature. For instance P205 can substitute for $102.

can substitute for each other and in some instances for CaO. Fe203, A1203, and M11203 can also substitute for each other. 7

I have found that slags which contain monticellite type silicate and a magnetic oxide do not have a manganese distribution favorable to the Apparently the manganese distributes itself between both the concentration of manganese.

oxide and silicate according to a complex equilibrium. Also, I have found that when any ferrites develop, manganese cannot be concentrated and the attainment of any concentrate is very diflicult.

But I have found that in a narrow and critical range, the lime, silica, and phosphorus oxides form a silicate which is relatively free from manganese, and the oxide will contain magnesium,

iron, and manganese in a surprisingly removable form. r

The chemical range through which my invention i operable may be defined as compositions of matter producing dicalcium silicate and a manganese-containing oxide. Alternatively, they might be defined as a composition in which the molar ratio of CaO--3P2O5 SiOz is ideally and preferably as 2:1. The invention is in general operable between ranges of 25:1

and 1.721 but deviations from the ideal to extreme ratios result in a decrease in recovery ifrom 3 about 9 1% to 921.

This simplification MnO, FeO, and MgO In t e P ti oimy nv iii en wl hraiilei em advantage I may utilize slag as it comes from open hearths or from old dumps. On an average such slag mixtures will require addition of from 5 to 20 parts limestone per hundred parts of slag for composition adjustment. Individual slags may requireea silica addition andlothersmay. re-

quire more. limestone. In, any case the: slag: is crushed and metallic iron removed and the correcting material is added in to bring the CaO3P205 SiOz ratio to 2:1. The mixture isthenpulverizedtd about -40 mesh, and is heated, toatemperature of about 2550 F., and cooled slowly. This firing operation can be accomplished in a rotary kiln, reverberatory furnace, etc., as in known practices; The product of these operations should be coarsely crystalline dicalcium silicate, and a mag netic oxide of iron which has taken up the man anese After cooling. the. slag is round: to. aboutzoll mesh. and, passedv over. magnetic.v separators... These, separators should give a tailing which, is. p actically. free. of. oxideanda middling con.- tamingv physically. attachedisilicate and oxide, and a mangagese concentrate relatively. free from silicate. The. middling, can hereround. and re.- cycled. to. the separatin circuit or to the, furnace, to give, practically. any degree of concentration desired.

It .may bepreferredlto leave a small amount of the. silicate, in the.concentrates. Such silicate wflllfilhQtiOn as a flux andjiinsubsequent,reducing operation may serve a useful purpose.

This silicate. willcontain a small amountof undesirable phosphorus. It'caneasily be removed by making about a. 30% slurry ofthe concentrate. in; water and; adding enough acid, to, neutralize theCaOtplus about a; excess and agitating for lo'to minutes; If the concentrates will-beinthe concentrates and' part' in" the tail-=.

ratio is carried on the highside, for example 2.1;:1; the alumina will be more concentrated in thetailings; ifon' the; low side; i. e. 1.9/1, in the concentrates. The tailings consistofa fine chemically active dicalcium silicate with P205 plus many traceelements: Its 'solubilityand composition make it useful for agricultural liming of soil.

The concentrate may next bereduced to spiegeleisen by; any convenient means such asblast'furnace, electric furnace, etc. The particularalloyobtainedwill depend upon'the ratio of iron--and manganese -in the-original'slag and upon conversion losses. Usually about 10% iron. and 20% manganese willibealost-inthe overall processing.

The following example is illustrative of my invention. I. take a mixtureof flushandfinishms slaes... ascomingirom ,thefurnace, having the following; composition:

The exact steps are subject. to variations MnO 11.? A1203 4.47 FeO 17.6 MgO 7.81

I correct as follows to a ratio of 2.1 to 1:

Molecular: equivalent of CaOJ, 32.6;'+5.6i==582; Molecular equivalent of Si02, 22.8+60=.381 Molecular equivalent of P205, 2.14+142=.015

Ca0-3(B20.5) oa 3(. 5

'SiO .381

Ca O =.8,4 5 Molecular equivalent of CaO required .582 Molecular, equivalent of CaO in slag our. e63 Molecular equivalent of CaO which must'be supplied.

I add to parts of slag, 25 parts of limestone whichgives approximately .26 molar part or 14.6 parts by Weight of C90.

This; mixture-.isz ground. to -40 ,mesh 1 and: fired: to about-.2550? Fhfor one-hour andslow-ly cooled. It then; comprises. coarse; dicalcium silicate, ina. matrix, ofvery. magnetic oxide.-. The clinker. is. as followsin. composition:

SiO2- 2012 P205 1.9 CaQ 40.9 A1203 39 FeO 1516 MgO 6i9 M 1014 Itherefore particularly point out and distinctly;-

claim as myinvention:

1'. Ina process of'obtainingan oxide of manganesefrom solid compound silicate material containing: calcium, iron and manganese, adding a material selected from the group consisting of oxygen-containing calcium and silicon materialsto said silicate material'fto give the mixture a molar ratio CaO3P O SiO; which ismore than -.1.7. to l but less thanv 2.5 to 1',

heating the mixturev to a temperature to produce.

dicalcium silicate and a magnetiemanganeseand iron oxideportion, cooling said-heated material, grinding the same, and recovering. saidmanganes e.;and iron oxide. portion.

2. In aprocess of obtaining an oxideof mangaa' mass. from solid compound, silicate-material. con-,1. taining' calcium. iron, manganese, and. phossrphorus, adclinev a, material. selected from. the; roup. consisting, of oxygenrcontaining; calcium. and silicon materials to said silicate material to. give.the mixture 2. molar ratio whichismOre than L'Tto rbut'less'than 255 190 1 heating the mixture to a temperature to produce dicalcium silicate and a magnetic manganese and iron oxide portion, cooling said heated material, grinding the same, and recovering said manganese and iron oxide portion.

3. In a process of obtaining an oxide of manganese from solid slag comprising a compound silicate material containing calcium, iron and manganese, adding a material selected from the group consisting of oxygen-containing calcium and silicon materials to said slag material to give the mixture a molar ratio SiOg which is more than 1.7 to l but less than 2.5 to 1,

heating the mixture to a temperature to produce dicalcium silicate and a magnetic manganese a d iron oxide portion, cooling said heated material,

grinding the same, and recovering said manganese and iron oxide portion.

4. In a process of obtaining an oxide of manganese from solid open hearth slag, adding a material selected from the group consisting of oxygen-containing calcium and silicon materials to said slag material to give the mixture a molar ratio iSiO which is more than 1.7 to 1 but less than 2.5 to l, heating the mixture to a temperature of about 2550 F. for about one hour to produce dicalcium silicate and a magnetic manganese and iron oxide portion, cooling said heated material, grinding.

the same, and recovering said manganese and iron oxide portion.

6. In a process of obtaining an oxide of manganese from solid open hearth slag, adding a material selected from the group consisting of oxygen-containing calcium and silicon materials to said slag material to give the mixture a molar ratio SiOZ which is more than 1.7 to 1 but less than 2.5 to 1, grinding such mixture to about 40 mesh, heating the mixture to a temperature to produce dicalcium silicate and a magnetic manganese and iron oxide portion, cooling said heated material, grinding the same, and recovering said manganese and iron oxide portion 7. In a process of obtaining an oxide of manganese from solid open hearth slag comprising compound silicate material containing calcium, iron and manganese, adding a material selected from the group consisting of oxygen-containing calcium and silicon materials to said slag material to give the mixture a molar ratio which is more than 1.7 to 1 but less than 2.5 to 1, grinding such mixture to about 40 mesh, heating the mixture to a temperature of about 2550 F. for about one hour to produce dicalcium silicate and a magnetic manganese and .iron oxide portion, cooling said heated material, grinding the same, and recovering said manganese and iron oxide portion.

8. In a process of obtaining an oxide of manganese from solid open hearth slag comprising compound silicate material containing calcium, iron, manganese and phosphorus, adding a material selected from the group consisting of oxygen-containing calcium and silicon. materials to said slag material to give the mixture a molar ratio C3'OV3P2O5 SiO of between 2.5 and 1.7 to 1, the steps comprising heating the material to a temperature of about 2550" F. to produce dicalcium silicate and a ma netic manganese and iron oxide portion, cooling said heated material, grinding the same, and recovering said manganese and iron oxide portion.

ROBERT A. SCHOENLAUB.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 556,457 Cabot et al Mar. 17, 1896 2,132,404 Dean Oct. 11, 1938 2,352,712 Heckett July 4, 1944 2,353,613 Gardner July 11, 1944 2,409,428 Gardner Oct. 15, 1946 2,471,562 Fitterer May 31, 1949 OTHER REFERENCES Chemical Abstracts, vol. 22, page 3380, Some Constituents of Open Hearth Slags, by J. M. Ferguson (1928).

1948 Open Hearth Proceedings, vol. 31, pages 194-200, published by A. I. M. M. E. 

3. IN A PROCESS OF OBTAINING AN OXIDE OF MANGANESE FROM SOLID SLAG COMPRISING A COMPOUND SILICATE MATERIAL CONTAINING CALCIUM, IRON AND MANGANESE, ADDING A MATERIAL SELECTED FROM THE GROUP CONSISTING OF OXYGEN-CONTAINING CALCIUM AND SILICON MATERIALS TO SAID SLAG MATERIAL TO GIVE THE MIXTURE A MOLAR RATIO 